首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1628篇
  免费   113篇
  国内免费   2篇
耳鼻咽喉   13篇
儿科学   44篇
妇产科学   56篇
基础医学   189篇
口腔科学   22篇
临床医学   207篇
内科学   281篇
皮肤病学   17篇
神经病学   177篇
特种医学   64篇
外科学   234篇
综合类   27篇
一般理论   3篇
预防医学   194篇
眼科学   47篇
药学   105篇
中国医学   2篇
肿瘤学   61篇
  2021年   18篇
  2019年   15篇
  2018年   26篇
  2017年   14篇
  2016年   14篇
  2015年   22篇
  2014年   37篇
  2013年   36篇
  2012年   56篇
  2011年   64篇
  2010年   22篇
  2009年   47篇
  2008年   73篇
  2007年   86篇
  2006年   70篇
  2005年   68篇
  2004年   61篇
  2003年   50篇
  2002年   58篇
  2001年   53篇
  2000年   53篇
  1999年   44篇
  1998年   20篇
  1997年   11篇
  1996年   18篇
  1995年   11篇
  1994年   16篇
  1993年   14篇
  1992年   43篇
  1991年   38篇
  1990年   37篇
  1989年   30篇
  1988年   31篇
  1987年   44篇
  1986年   39篇
  1985年   33篇
  1984年   28篇
  1983年   19篇
  1982年   25篇
  1979年   27篇
  1978年   22篇
  1977年   11篇
  1974年   16篇
  1973年   12篇
  1971年   10篇
  1970年   17篇
  1969年   15篇
  1968年   17篇
  1967年   18篇
  1966年   16篇
排序方式: 共有1743条查询结果,搜索用时 31 毫秒
41.

Objective

To investigate the safety and efficacy of etanercept in the treatment of uveitis associated with juvenile idiopathic arthritis (JIA).

Methods

Children who met the American College of Rheumatology diagnostic criteria for JIA with active uveitis, who had anterior chamber cells of ≥1+ or requiring topical corticosteroid ≥3 times daily, and who were on a stable regimen for arthritis treatment were eligible. Study participants received etanercept (0.4 mg/kg) or placebo administered subcutaneously twice weekly for 6 months. All participants received open‐label etanercept for an additional 6 months.

Results

Five patients received placebo and 7 received etanercept. Three of the 7 patients treated with etanercept and 2 of the 5 placebo‐treated patients were considered ophthalmic successes (P = 1.0). One patient in each treatment group was considered a treatment failure. Three of the 7 etanercept‐treated and 2 of the 5 placebo‐treated patients were neither successes nor failures by our definition. There were no serious adverse events for any patient during the entire study period. Reports of minor infections were comparable in each treatment group, 71% for etanercept and 60% for placebo (P = 0.58).

Conclusion

In this small pilot study there was no apparent difference in the anterior segment inflammation between patients treated with etanercept and placebo. The stringent criteria used to measure ophthalmic success of treatment and the small patient population limit the implications of our findings.
  相似文献   
42.
Objectives Our goals were to compare the characteristics of patients with and without prior coronary artery bypass graft (CABG) presenting with acute myocardial infarction (MI) with or without ST elevation/left bundle branch block (LBBB), and to evaluate the effect of ST shift on inhospital mortality. Methods and Results Using the National Registry of Myocardial Infarction-3 Registry, we identified 112,697 patients with acute MI without exclusion criteria. Of these, 15,936 (14.1%) had prior CABG. Patients with prior CABG had more adverse characteristics and were less likely to have ST elevation/LBBB than patients without prior CABG. The unadjusted mortality for ST elevation/LBBB patients was higher in patients with prior CABG versus without (16.2% vs 14.1%, P = .0001), whereas in patients without ST elevation/LBBB, prior CABG conferred a lower unadjusted mortality versus without (10.1% vs 12.4%, P = .0001). Adjusting for baseline differences, prior CABG was weakly associated with inhospital mortality in ST elevation/LBBB patients (odds ratio [OR], 1.11, 95% CI 1.00-1.23), but not in patients without ST elevation/LBBB (OR 0.99, 95% CI 0.92-1.07). Conclusion Acute MI patients with prior CABG are more likely to present without ST elevation/LBBB than patients without prior CABG. Prior CABG was weakly associated with inhospital mortality in patients with ST elevation/LBBB, but not in patients without these electrocardiographic findings. This suggests the differences in absolute mortality rates between patients presenting with MI with and without a history of prior CABG are largely caused by differences in baseline characteristics and presentation. (Am Heart J 2002;144:463-9.)  相似文献   
43.

Introduction

Given the biological complexity of the ageing process, there is no single, simple and reliable measure of how healthily someone is ageing. Intervention studies need a panel of measures which capture key features of healthy ageing. To help guide our research in this area, we have adopted the concept of the “Healthy Ageing Phenotype” (HAP) and this study aimed to (i) identify the most important features of the HAP and (ii) identify/develop tools for measurement of those features.

Methods

After a comprehensive assessment of the literature we selected the following domains: physiological and metabolic health, physical capability, cognitive function, social wellbeing, and psychological wellbeing which we hoped would provide a reasonably holistic characterisation of the HAP. We reviewed the literature and identified systematic reviews and/or meta-analysis of cohort studies, and clinical guidelines on outcome measures of these domains relevant to the HAP. Selection criteria for these measures included: frequent use in longitudinal studies of ageing; expected to change with age; evidence for strong association with/prediction of ageing-related phenotypes such as morbidity, mortality and lifespan; whenever possible, focus on studies measuring these outcomes in populations rather than on individuals selected on the basis of a particular disease; (bio)markers that respond to (lifestyle-based) intervention. Proposed markers were exposed to critique in a Workshop held in Newcastle, UK in October 2012.

Results

We have selected a tentative panel of (bio)markers of physiological and metabolic health, physical capability, cognitive function, social wellbeing, and psychological wellbeing which we propose may be useful in characterising the HAP and which may have utility as outcome measures in intervention studies. In addition, we have identified a number of tools which could be applied in community-based intervention studies designed to enhance healthy ageing.

Conclusions

We have proposed, tentatively, a panel of outcome measures which could be deployed in community-based, lifestyle intervention studies. The evidence base for selection of measurement domains is less well developed in some areas e.g. social wellbeing (where the definition of the concept itself remains elusive) and this has implications for the identification of appropriate tools. Although we have developed this panel as potential outcomes for intervention studies, we recognise that broader agreement on the concept of the HAP and on tools for its measurement could have wider utility and e.g. could facilitate comparisons of healthy ageing across diverse study designs and populations.  相似文献   
44.
CardioVascular and Interventional Radiology - To compare lung shunt fraction (LSF) prior to Y-90 radioembolization calculated using planar imaging versus SPECT/CT in patients with hepatocellular...  相似文献   
45.
46.
47.
Anabolic‐androgenic steroids are synthetic compounds prohibited due to their performance‐enhancing characteristics. The use of these substances is known to cause health‐related issues, which highlights the importance of being able to evaluate the scale of consumption by the general population. However, most available research on the analysis of anabolic steroids is focused on animals and athletes in connection with doping. The potential of wastewater‐based epidemiology as an intelligence tool for the assessment of community level use of anabolic steroids is presented herein. A liquid chromatography tandem mass spectrometry method was developed for the analysis of 10 anabolic‐androgenic steroids and 14 endogenous hormones in influent wastewater. The validated method was applied to sixteen 24‐hour composite wastewater influent samples that were collected over a period of five years from two wastewater treatment plants in Queensland, Australia. Nine investigated compounds were found to be present at concentrations between 14 and 611 ng L?1 which translated into 3–104 mg excreted per 1000 individuals per day. It was concluded that the developed analytical method is suitable for the analysis of AAS in wastewater matrix. Additionally, both the inclusion of metabolites and further investigation into deconjugation by enzymatic hydrolysis would aid in understanding and evaluating community anabolic steroid use. For the first time, this study presents the application of wastewater‐based epidemiology on anabolic‐androgenic steroids in Australia.  相似文献   
48.
While the role of collagen and elastin fibrous components in heart valve valvular biomechanics has been extensively investigated, the biomechanical role of the glycosaminoglycan (GAG) gelatinous-like material phase remains unclear. In the present study, we investigated the biomechanical role of GAGs in porcine aortic valve (AV) leaflets under tension utilizing enzymatic removal. Tissue specimens were removed from the belly region of porcine AVs and subsequently treated with either an enzyme solution for GAG removal or a control (buffer with no enzyme) solution. A dual stress level test methodology was used to determine the effects at low and high (physiological) stress levels. In addition, planar biaxial tests were conducted both on-axis (i.e. aligned to the circumferential and radial axes) and at 45° off-axis to induce maximum shear, to explore the effects of augmented fiber rotations on the fiber–fiber interactions. Changes in hysteresis were used as the primary metric of GAG functional assessment. A simulation of the low-force experimental setup was also conducted to clarify the internal stress system and provide viscoelastic model parameters for this loading range. Results indicated that under planar tension the removal of GAGs had no measureable affect extensional mechanical properties (either on- or 45° off-axis), including peak stretch, hysteresis and creep. Interestingly, in the low-force range, hysteresis was markedly reduced, from 35.96 ± 2.65% in control group to 25.00 ± 1.64% (p < 0.001) as a result of GAG removal. Collectively, these results suggest that GAGs do not play a direct role in modulating the time-dependent tensile properties of valvular tissues. Rather, they appear to be strongly connected with fiber–fiber and fiber–matrix interactions at low force levels. Thus, we speculate that GAGs may be important in providing a damping mechanism to reduce leaflet flutter when the leaflet is not under high tensile stress.  相似文献   
49.
Randomized controlled trials (RCTs) have suggested a potential advantage of dose-dense chemotherapy in improving disease-free and overall survival in patients with certain malignancies. This systematic review summarizes the literature on the efficacy of dose-dense chemotherapy across various cancers (breast cancer, non-Hodgkin lymphoma [NHL], and non-small cell lung cancer) and chemotherapy regimens. Among the 17 trials identified, few reported statistically significant differences between dose-dense and standard chemotherapy, and most were small with limited statistical power. Statistically significant differences in overall survival favoring dose-dense schedules were apparent among large RCTs in potentially curative settings such as early-stage breast cancer and NHL. Clinical and treatment heterogeneity demonstrated the flexibility of the dose-dense paradigm but also precluded quantitative meta-analysis of results. Further study of dose-dense schedules based on large RCTs is needed to demonstrate the consistency and generalizability of these findings.  相似文献   
50.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号